Toxins are poisonous substances produced within living cells or organisms. Toxins such as mycotoxins are a chemically variable group of secondary metabolites of fungi, which can be found in grains and other feedstuffs even in the absence of any visible fungal growth. High temperature and air humidity during the storage increase the likelihood of fungal growth, but mycotoxin contamination can also occur already in the field. Visible appearance or smell of grains or silage does not indicate the presence or absence of mycotoxin contamination. Effects of toxins such as mycotoxins to farm animals are very variable, and range from increased mortality to decreased fertility and performance. Mycotoxins may also disturb the immune system of animals and make them more susceptible to diseases.
Due to the chemical variability of mycotoxins, analysis of all feedlots for even the most common mycotoxins would be too expensive. Therefore mycotoxin adsorbents are often used to give extra insurance against mycotoxin contamination in feeds. Mycotoxin adsorbents are substances that are itself not digested or absorbed by the animal. They are assumed to bind toxins during the passage through the alimentary canal. Thus, instead of being absorbed by the animals, the toxins get eventually voided via feces.
Toxin binders can also adsorb other types of toxins, like bacterial toxins or secondary metabolites of plants from the digestive tract. Activated carbon (charcoal), which is a fine-granulated powder with a porous microstructure, is an efficient toxin binder. It is a recommended general toxin binder in various poisonings. However, charcoal also binds vitamins and minerals, which makes it unsuitable for continuous use in feeds. Silicate clays are also used as adsorbents in feeds.
Fractional distillation of crude tall oil, obtained as a by-product of the Kraft process of wood pulp manufacture, produces distilled tall oil (DTO) which typically comprises over 10% resin acids and less than 90% fatty acids. Further refinement of distilled tall oil produces the tall oil fatty acid (TOFA), which is available in a variety of compositions differing in the fatty acids and resin acids content. Because the TOFA is an inexpensive source of fatty acids, it has previously been used in animal nutrition as an energy source. For instance, GB 955316 discloses the use of alkali metal salts of tall oil fatty acids to improve weight gain and nitrogen retention in ruminant animals.